Even though the H7N9 bird flu killed 44 people in China in 2013, the virus still appears to be better adapted to infecting birds.

Researchers studied the structure of proteins from one strain of the H7N9 virus that caused the outbreak and tested how strongly one of the proteins bound to molecules on the surfaces of bird and human cells. The structure of the virus appears to be better adapted and to attach more strongly to the bird molecules compared with human molecules, the team reports Decem...